Improve completion: src/<tab> will now correctly complete to src/main.rs

3 files changed, 33 insertions, 26 deletions

diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index f84bb16e..54fea453 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -723,20 +723,26 @@ pub fn command_mode(cx: &mut Context) {
             // simple heuristic: if there's no space, complete command.
             // if there's a space, file completion kicks in. We should specialize by command later.
             if parts.len() <= 1 {
+                use std::{borrow::Cow, ops::Range};
+                let end = 0..;
                 COMMAND_LIST
                     .iter()
                     .filter(|command| command.contains(input))
-                    .map(|command| std::borrow::Cow::Borrowed(*command))
+                    .map(|command| (end.clone(), Cow::Borrowed(*command)))
                     .collect()
             } else {
                 let part = parts.last().unwrap();
                 ui::completers::filename(part)
+                    .into_iter()
+                    .map(|(range, file)| {
+                        // offset ranges to input
+                        let offset = input.len() - part.len();
+                        let range = (range.start + offset)..;
+                        (range, file)
+                    })
+                    .collect()
 
                 // TODO
-                // completion needs to be more advanced: need to return starting index for replace
-                // for example, "src/" completion application.rs needs to insert after /, but "hx"
-                // completion helix-core needs to replace the text.
-                //
                 // additionally, completion items could have a info section that would get
                 // displayed in a popup above the prompt when items are tabbed over
             }
diff --git a/helix-term/src/ui/mod.rs b/helix-term/src/ui/mod.rs
index f7ba59cd..b35cba60 100644
--- a/helix-term/src/ui/mod.rs
+++ b/helix-term/src/ui/mod.rs
@@ -137,9 +137,9 @@ pub fn buffer_picker(views: &[View], current: usize) -> Picker<(Option<PathBuf>,
 }
 
 pub mod completers {
-    use std::borrow::Cow;
+    use std::{borrow::Cow, ops::RangeFrom};
     // TODO: we could return an iter/lazy thing so it can fetch as many as it needs.
-    pub fn filename(input: &str) -> Vec<Cow<'static, str>> {
+    pub fn filename(input: &str) -> Vec<(RangeFrom<usize>, Cow<'static, str>)> {
         // Rust's filename handling is really annoying.
 
         use ignore::WalkBuilder;
@@ -163,6 +163,8 @@ pub mod completers {
             (path, file_name)
         };
 
+        let end = (input.len()..);
+
         let mut files: Vec<_> = WalkBuilder::new(dir.clone())
             .max_depth(Some(1))
             .build()
@@ -178,10 +180,11 @@ pub mod completers {
                     if is_dir {
                         path.push("");
                     }
-                    Cow::from(path.to_str().unwrap().to_string())
+                    let path = path.to_str().unwrap().to_string();
+                    (end.clone(), Cow::from(path))
                 })
             }) // TODO: unwrap or skip
-            .filter(|path| !path.is_empty()) // TODO
+            .filter(|(_, path)| !path.is_empty()) // TODO
             .collect();
 
         // if empty, return a list of dirs and files in current dir
@@ -195,15 +198,20 @@ pub mod completers {
             // inefficient, but we need to calculate the scores, filter out None, then sort.
             let mut matches: Vec<_> = files
                 .into_iter()
-                .filter_map(|file| {
+                .filter_map(|(range, file)| {
                     matcher
                         .fuzzy_match(&file, &file_name)
                         .map(|score| (file, score))
                 })
                 .collect();
 
+            let range = ((input.len() - file_name.len())..);
+
             matches.sort_unstable_by_key(|(_file, score)| Reverse(*score));
-            files = matches.into_iter().map(|(file, _)| file).collect();
+            files = matches
+                .into_iter()
+                .map(|(file, _)| (range.clone(), file))
+                .collect();
 
             // TODO: complete to longest common match
         }
diff --git a/helix-term/src/ui/prompt.rs b/helix-term/src/ui/prompt.rs
index 19885c02..35890b4c 100644
--- a/helix-term/src/ui/prompt.rs
+++ b/helix-term/src/ui/prompt.rs
@@ -3,16 +3,15 @@ use crossterm::event::{Event, KeyCode, KeyEvent, KeyModifiers};
 use helix_core::Position;
 use helix_view::Editor;
 use helix_view::Theme;
-use std::borrow::Cow;
-use std::string::String;
+use std::{borrow::Cow, ops::RangeFrom};
 
 pub struct Prompt {
     prompt: String,
     pub line: String,
     cursor: usize,
-    completion: Vec<Cow<'static, str>>,
+    completion: Vec<(RangeFrom<usize>, Cow<'static, str>)>,
     completion_selection_index: Option<usize>,
-    completion_fn: Box<dyn FnMut(&str) -> Vec<Cow<'static, str>>>,
+    completion_fn: Box<dyn FnMut(&str) -> Vec<(RangeFrom<usize>, Cow<'static, str>)>>,
     callback_fn: Box<dyn FnMut(&mut Editor, &str, PromptEvent)>,
 }
 
@@ -29,7 +28,7 @@ pub enum PromptEvent {
 impl Prompt {
     pub fn new(
         prompt: String,
-        mut completion_fn: impl FnMut(&str) -> Vec<Cow<'static, str>> + 'static,
+        mut completion_fn: impl FnMut(&str) -> Vec<(RangeFrom<usize>, Cow<'static, str>)> + 'static,
         callback_fn: impl FnMut(&mut Editor, &str, PromptEvent) + 'static,
     ) -> Prompt {
         Prompt {
@@ -85,15 +84,9 @@ impl Prompt {
             self.completion_selection_index.map(|i| i + 1).unwrap_or(0) % self.completion.len();
         self.completion_selection_index = Some(index);
 
-        let item = &self.completion[index];
+        let (range, item) = &self.completion[index];
 
-        // replace the last arg
-        if let Some(pos) = self.line.rfind(' ') {
-            self.line.replace_range(pos + 1.., item);
-        } else {
-            // need toowned_clone_into nightly feature to reuse allocation
-            self.line = item.to_string();
-        }
+        self.line.replace_range(range.clone(), item);
 
         self.move_end();
         // TODO: recalculate completion when completion item is accepted, (Enter)
@@ -135,7 +128,7 @@ impl Prompt {
                 Rect::new(0, area.height - col_height - 2, area.width, col_height),
                 theme.get("ui.statusline"),
             );
-            for (i, command) in self.completion.iter().enumerate() {
+            for (i, (_range, completion)) in self.completion.iter().enumerate() {
                 let color = if self.completion_selection_index.is_some()
                     && i == self.completion_selection_index.unwrap()
                 {
@@ -146,7 +139,7 @@ impl Prompt {
                 surface.set_stringn(
                     1 + col * BASE_WIDTH,
                     area.height - col_height - 2 + row,
-                    &command,
+                    &completion,
                     BASE_WIDTH as usize - 1,
                     color,
                 );